In case you were wondering why we use British English for our definitions, it's simply because the site is UK-based, and we're all Brits! For words alternative American spellings, we've included these in these in the definitions, so hopefully this is useful to our huge number of much-valued users in the US.
A few of you have got in touch to tell us you can't find definitions when you search for the American English spelling. We have recently made some changes that mean if you search for a US spelling it redirects you to the British English version and the definition. However there do seem to be occassions when this isn't happening - we are working on fixing these, so if you notice any instances when it's not working, please get in touch and let us know.